1. Field
This disclosure relates generally to MEMs devices, and more specifically, to a MEMs capacitor device with a conductively tethered moveable capacitor plate.
2. Related Art
A MEMS capacitor is one of the most important tunable devices required by re-configurable radio-frequency (RF) systems. In a piezoelectrically actuated MEMS capacitor device, the mechanical formation is predominantly determined by the requirements of the actuator design, the mechanical formation including material choices, thicknesses and stresses of the thin film layers of the moveable structures. As a result, this makes it very difficult to use the same material composites to design a good quality moveable MEMS capacitor plate that meets its own corresponding mechanical, thermal and electrical/RF requirements.
For improved RF performance, a transmission line for use in connecting the moveable MEMS capacitor plate to another part of the RF circuit will most likely require a different metal material and thickness than corresponding ones of the piezoelectric actuator electrodes. This makes it difficult to design a moveable connection structure that has minimum impact to the thermal mechanical performance of the overall device. At the same time, an electrically isolated (i.e., electrically “floating”) capacitor plate design significantly reduces the capacitance density of the MEMS capacitor.
Accordingly, there is a need for an improved method and apparatus for overcoming the problems in the art as discussed above.